This invention relates to methods and apparatus for cutting vegetation and the like, and more particularly relates to improved methods and apparatus for cutting vegetation with a flexible non-metallic string or line member or the like.
Lawn mowers and trimmers which employ a moving steel blade are well known, but are also well known to be subject to certain inherent disadvantages. In particular, such devices cannot reach vegetation which is adjacent fences, walls, trees and the like. More especially, any device which revolves a rigid metallic blade at a relatively high velocity is inherently dangerous to persons and property within its vicinity. However, these and other disadvantages of conventional cutters have now been overcome with a type of trimmer which employs a flexible non-metallic string or line, and which is more particularly described in U.S. Pat. No. 3,708,967; No. 3,826,068; and No. 3,859,776.
Contrary to presupposition, a plastic string can usually cut vegetation almost indefinitely without breaking, provided the string engages only vegetation of the type sought to be cut. On the other hand, it will also be apparent that if a plastic string does impact against a resistive object, such as a concrete wall or chain link fence or the like, the string or line will be more likely to break than will a rigid steel blade. Since this type of cutter is expressly intended to be used to cut vegetation adjacent such resistive objects, it will not be surprising that the string or line will often experience breakage, and that the string or line must therefore be replaced from time-to-time.
As shown in the aforementioned patents, it has been found necessary and desirable to provide these trimmers with a spool having a substantial length of cutting line coiled therein, and to employ only a short unwound portion of the line as the cutting member. Thus, if a portion of the extended cutting portion of the line becomes damaged or broken, the cutting member may be quickly and inexpensively replaced by merely manually unwinding a new portion of line from the spool, and extending this unwound portion to form the new cutting member.
This manner of providing replacement cutting line has been found to be subject to certain problems, however. As may be seen in the aforementioned patents, it is desirable to protect the coiled portion of the line from moisture and debris by enclosing it in a circular head member, and to extend the unwound portion through a peripheral aperture in this head member to form the cutting member. Therefore, if the string breaks at a point at or within the head member, it is often necessary to remove and disassemble the head member in order to gain access to the head member.
Another problem with providing for manually unwinding cutting line from its spool arises from the fact that the spool is recessed snugly within the circular head member to prevent the line from escaping from the spool and head member during revolvement of the spool and head member. Thus, when it is desired to withdraw or unwind more cutting string, it is necessary to draw the string about the edge of the flange of the spool, while the string is wedged between the rim of the flange and the surface of the housing, and this tends to damage the cutting line or string. Either that, or else it is necessary to bend the flange away from the head to provide more clearance from the cutting line, which tends to damage the spool. In either case, it will be apparent that this, in turn, tends to greatly reduce the overall convenience of this type of cutting apparatus, and to create an operating problem which is not present in more conventional cutters.
It has been proposed to overcome this and other related disadvantages by providing such equipment with means for mechanically extending or feeding out lengths of cutting line from the head member whenever desired. In this regard, a mechanical feed mechanism has been proposed in U.S. Pat. No. 3,664,102, which is designed for use with apparatus employing a plurality of metallic wires as cutting members. Such a feed mechanism is clearly not appropriate, of course, in apparatus employing only a single flexible cutting line, and especially when the line is formed of a plastic rather than a metal.
These disadvantages of the prior art are overcome with the present invention, and novel means and methods for cutting vegetation are herewith provided with feed means and techniques whereby plastic cutting line may be fed out of the cutting head without incurring damage to the cutting line or any other portion of this apparatus.